Quantum Projectors Implemented With Optical Directional Couplers in Ion-Exchanged Glasses

Ion-exchanged glass as a platform for quantum photonics is proposed. Quantum projectors are implemented with integrated optical directional couplers fabricated by ion-exchange K $^+$ /Na $^+$ in soda-lime glass. We consider devices composed of concatenated directional couplers which implement $N$ -dimensional quantum projective measurements, and concomitantly the production of 1-qudit states. The fundamental units of these devices are 2 × 2 directional couplers that are experimentally studied in order to obtain, through an optical characterization, empiric relationships between fabrication and optical parameters of such couplers. Likewise, a two-dimensional quantum projector is demonstrated so that projective measurements are obtained for the states of bases X (diagonal) and Y (circular).